Method for producing a synthesis gas



March 2, 1954 c. w. WATSON 2,671,013

METHOD FOR PRoDucING A SYNTHESIS GAS Filed Nov. l1o, 1949- 2 sheets-sheer 1 JNVENToR. 62 @DE WWATso/v BY %MATTORNEYS' March 2, 1954 c. w. wATsoN 2,671,013

METHOD FOR PRoDucING A SYNTHESIS GAS Filed Nov. 10. 1949 2 sheets-sheet 2 Patented Mar. 2, 1954 METHOD FOR PRODUCING A SYNTHESIS GAS Claude W. Watson, Port Arthur, Tex., assignor to The Texas Company, New York, N. Y., a corporation of Delaware Application November 10, 1949, Serial No. 126,491

. 7 Claims.

1 The present invention relates generally to the catalytic synthesis of hydrocarbons, oxygenated hydrocarbons and mixtures thereof, and broadly is concerned with the preparation of a stream of synthesis gas comprising hydrogen and carbon oxide, particularly a mixture of hydrogen and carbon monoxide suitable as a reactant feed for catalytic conversion to said desired synthetic products.

`In particular, the present invention contem plates the preparation of synthesis gas from a Acarbonaceous feed material containing hydrogen by reaction With a readily carbidable and subsequently decarbidable metal at the elevated temperature at which decomposition takes place to liberate free hydrogen and form a carbide of the metal. The term readily carbidable and subsequently decarbidable metal as used herein means manifestly a metal which readily combines with carbon to form a carbide, which in turn, is readily decarbidable.

The carbidable metal subjected to reaction with the carbonaceous feed is preferablyv formed by reduction of previously carbided metal particles. at elevated temperatures, with carbon dioxide. The previously carbided and decarbided Vmetal is highly reactive with the carbonaceous feed to effect the desired decomposition thereof and a high rate of decarbiding.

Reduction of the metal carbide by carbon dioxide to the relatively or substantially decarbided form simultaneously yields a substantial stream vof carbon monoxide, quite materially in excess of the carbon dioxide supplied. The decarbided metal may be returned, preferably continuously, lto effect decomposition of fresh carbonaceous feed material.

A particular feature of the present invention involves the continuous conversion of a portion of the product carbon monoxide thus :formed into carbon dioxide by reaction, at an elevated temperature, with a stream of a readily reducible metal oxide. In this manner, a small portion of the carbon monoxide produced is continuously converted into suicient carbon dioxide to eiect the reduction of the metal carbide formed, yielding overall a substantial excess of carbon monoxide Which may be withdrawn and intermixed with the product hydrogen to form a synthesis gas of the desired composition. A

' Operating inthis manner, the metal oxide is advantageously regenerated and returned, preferably continuously, for oxidation of additional carbon monoxide. vThis regeneration is Aprefere ably eiected byhightemperature contact of the reduced metal oxide particles with high pressure steam or water vapor under conditions effective to return the metal to a high state of oxidation and yield incidentally an additional high stream of pure gaseous hydrogen.

The invention accordingly has the advantage of producing gaseous hydrogen and carbon mon-- oxide in a mol ratio which is high as regards free hydrogen content. Actually, it will be apparent that even with continuous diversion of product carbon monoxide to form the carbon dioxide required for decarbiding the carbidable metal, the theoretical yield of hydrogen and carbon monoxide from the carbiding and decarbiding steps corresponds to the stoichiometric equivalent of the carbon and hydrogen in the original hydrocarbonaceous feed.

Moreover, the additional free hydrogen formed by the continuous regeneration or reoxidation of the metal oxide substantially supplements the synthesis gas yield and desirably raises the overall portion of free hydrogen in the case of carbonaceous feeds containing relatively loW proportions of hydrogen.

On the other hand, with feed materials relatively high in hydrogen, such for example, as methane and other hydrocarbon gases, the excess of hydrogen may be advantageous in improving the yield of hydrocarbons, revivifying the catalyst and, in general, providing a valuable by-product credit.

The present invention has the further important effect of permitting Wide iiexibility of operation, since manifestly, the amount of product carbon monoxide which is diverted to form the stream of carbon dioxide for reduction of the iron carbide may be Widely varied, dependent upon the availability of carbon dioxide from outside sources.

For example, the subsequent catalytic production of desired hydrocarbon fractions from the synthesis gas thus producednormally results in a substantial yield of by-product carbon dioxide, Which in itself is variable over a wide range, depending upon the catalyst employed, reaction conditions and the like. This by-product carbon dioxide may be recovered andv substituted for any portion of the carbon dioxide formed by the oxidation of the product carbon monoxide, thus, in effect, permitting Wide variation in the amount of carbon monoxide'withdrawn in the synthesis gas.

It is to be noted, moreover, that the production of gaseous hydrogen during regeneration of the readily reducible metal oxide, in general, varies with the quantity of product carbon monoxide being converted to carbon dioxide thereby. In short, as less carbon monoxide is converted into carbon dioxide by the metal oxide, steam regeneration correspondingly decreases. Therefore, as extraneous carbon dioxide is substituted, the production of hydrogen is lessened and the product ratio of hydrogen to carbon monoxide decreases.

In this`V way, theprocess lends itself particularly to the production of synthesis gas of any desired ratio of hydrogen to carbon monoxide from feed materials of varying atomic H/(` ratio, and in addition, enables the production of relatively pure streams of either of these compo,- nents.

The invention in its broadest sense enables production of high purity synthesis gas without the requirement for high purity rectified oxygenv hitherto demanded out of practical necessity.

In addition, it provides an essentially self-contained system inherently capable of high yields.

In accordance with one advantageous modi ilcation, vvdecarbiding of the metal carbide and reduction of the readily reducible metal oxide may be effected simultaneously in a single zone Where both reactions go forward cooperatively irl the presence vof eachother to yield the metal iii essentiallyV elemental form, thus, in effect, obviating one processing step.

I n order to enable comprehension` of the invention in further detail, reference is madeA to the attached drawing wherein Figure I is a flow sheet illustrating one` embodiment of the present invention in rather elemental form, and Figure II represents an alternative arrangement in whichdecarbiding of the metal carbide is effected simultaneously with reduction of the readilyreducible metal oxide to effect mutual completen 5f-the desired reactions.

I In Figure I, an incoming stream of carbonac eous` feed material, preferably in the form of a gas or vapor at 1090" F. or higher, passes from any. suitable source not shown through inlet pipe l0 intoVV duct I2 where it joins the lower portion Qf. Starlsipipe l I 'Ihe ca rbonaceous feed is preferably a hydrocarbon, ranging anywhere from a gaseous fraction such as methane or natural gas to higher boiling fractions of the, gas oil or residual fuel oil, range. Provision, not shown, is best made by preheating the steam fed to pipe It tothe level indicated. and preferably as hig-h as feasiblewithout substantial cracking.

The preheatedy feed stream picks up, at the bottom ofstandpipe l I, nely divided solid particles ofY readily carbidable or decarbidable metal previously decarbided, as will hereinafter more fully appear, and carries them as a suspension through pipe i2 into the lower portion of cariiO hidingY reactor I 4. The suspension of the particles in the reactant vapors passes upwardly at a slow rate and at a temperature substantially above 100 0 F. and above 1300" F., during which the'hydrocarbon is decomposed, to yield ay gaseous effluent composed essentially of hydrogen, and to carbide the metal particles.

' Manifestly, therefore, the amount of metal particles fed into the reactor It with the hydrof carbon feed stream should be suicient to combine with all the carbon of the decomposed feed material as a metal carbide. Accordingly, it is preferred to supply a substantial excess over and above the stoichiometric quantities indicated by Atheamount-of carbon in the carbonaceousgfeed.

In this way, decomposition of the feed is carried close to completion at good reaction rates.

It is to be noted that the reactor i4, as well as the similarly symbolized reactor hereinafter described, are represented only diagrammatically, and therefore, should include provision, not shown, for maintaining the reactants at the elevated temperatures required'to thermally support the reaction. For example, firing chambers, electrical heating elements or any other conventional equivalents may be provided for maintaining 'the interior of the reactors at the specified temperature levels.

Moreoven in place of an upwardly moving suspension of solid particles and vapors disclosed, a mass ofthesolid particles may be held in dense fluid phase condition by flowing the vapors upwardlytherethrough, with continuous withdrawal of the product gas from thc upper pseudoliquid level thereof. In such case, introduction of the solid particles preferably takes place at the upper portion of the reaction zone with bottom draw-off to. effect an essentially countercurrent contact. However', catalyst introduction and withdrawal may be reversed and, similarly, provision may be made for passing the catalyst through the reactor in either direction as an 11nfluidi/ded moving bed.

In any event, the gasiform product eiiluent of reactor I passes into gas-solid separator I6 which removes anyparticles of metal carbide from the product streamy of hydrogen, thelatter passing overhead through pipe I'I while the separated particles` of highly carbided metal dis,- charge downwardly through said pipe i8.

The -specic form of separator is manifestly, per se, immaterial to the present invention and may comprise a filter or any effective Cyclonic, electrostatic, or any other conventional gassolid separating means. In the embodiments where magnetic particles are involved, magnetic separators are obviously indicated.

Passing downwardly in the standpipe I8, the metal carbide is in turn picked up in a stream of carbon dioxide injected through pipe I9, and carried asV a suspension` throughpipeV 2 6 into the lower portion of decarbiding reactor 2l,

In reactor 2| again at a temperature substantially above 1000o F. and Preferably above 1,300n F., theY carbon dioxide reacts with the metal carbidev to form carbon monoxide and return the carbided metal toits essentially elemental form. Accordingly, as above intimated,y the metal particles are withdrawnV aftersubstantial decarbiding and before any appreciable or substantial portion of the metal has been converted to an oxide, which would impair the desired hydro,- carbon decomposition.

Separation of the decarbided particles from the product gas takes place in separator 22, the residual stream of carbon monoxide passing overhead through pipe` 23- while the separated particles discharge-into stand-pipe ll, previously mentioned.v

Therefore,` in thel system thus far described, the readily reducible carbidable and decarbidable metal. particles` continuously, cycle between decarbiding. zonev where the vreaction occurs with carbon dioxide to form carbon monoxide, and

a carbiding zone l 4 Where. they are carbided by contactl with. thev fresh carbcnaceousA feed, producing free hydrogen, and aidecarbiding, zone 2|-, wherethey are decarbided` byvcontact with carbon dioxidetoform product carbon monoxide. In reared. is this y system. .reiernee is; had@ monoxide.

`faurrrpra my copending application, Serial No.` 126,492, led of even date herewith, wherein this method is described and claimed.

Of the carbon monoxide stream in line 23, a substantial proportion passes into branch pipe 25 and the remainder up to an amount Vcorresponding with the mol quantity of carbon dioxide consumed in decarbiding reactor 2 I, passes as shown into pipe 21, where it picks up and entrains finely powdered, readily reducible metal oxide delivered through standpipe 26.

The suspension of metal oxide in the carbon monoxide stream passes into the bottom of a reactor 28 where reaction occurs at an elevated temperature above 1000 F., and preferably above 1500 F. with substantial reduction of the metal oxide and oxidation of the carbon monoxide into carbon dioxide. As before, separation of ventrained solid particles from the product carbon dioxide takes place in a separator 35, the residual carbon dioxide being delivered overhead into pipe I9, previously mentioned, and the reduced metal oxide being discharged into standpipe 3I.

Regeneration of the reduced metal oxide is effected by a stream of high temperature steam injected from any suitable source not shown through pipe 32, which entrains the particles at the bottom of standpipe 3| and transports them through line 33 into the bottom of reactor 35. Temperature in the reactor 35 may be maintained as low as about 400 F., when the readily oxidizable metal is in relatively finely powdered form. However, temperatures as high as 1000o F. and over are usually accompanied by asubstantial increase in the rate of reaction and purity of the product stream. As above mentioned, the products of reaction pass into a separator 36 from which hydrogen ows overhead through pipe 31 and the regenerated metal particles are discharged into standpipe 26, previously mentioned.

In operation, therefore, at least a portion of the carbon dioxide required for decarbiding of the carbon carrier particles in reactor 2| is formed by continuously reoxidizing a portion of the product carbon monoxide withdrawn from this reactor.

Since regeneration of the metal oxide by water vapor results in a substantial supplementary stream of hydrogen, vent pipe 38 is preferably provided for withdrawing any desired portion as a relatively pure stream. Vent pipe 39 in line 25 permits withdrawal of relatively pure carbon However, the remaining hydrogen and carbon monoxide in lines I 1 and 31 flow into line 25, where they mix in the desired ratio and advantageously pass through condenser 4I! to decanter 4I for the separation of contained water vapor which is drawn .off through tap 42.

The resulting dry synthesis gas passes through line 44 into the bottom of the synthesis reactor 45, which may take any conventional form, but preferably contains a uidized mass of hydrocarbon synthesis catalyst 46, maintained at a regulated temperature by indirect exchanger 41.

The effluent gasiform .products of reaction emerge from the upper surface of the catalyst into the disengagement space and pass through filter 48 into line 49 leading through condenser 56 into separator 5I. Therein, the condensed `oil layer separates and is withdrawn throughl pipe 53, the condensed water is discharged through pipe 54 and the residual tail gas passes overhead as at '55. After venting any desired portion of: the tailgas as at 56, the remainder Y and carbon monoxide. The residual product gas from gas plant 59 passes through pipe 62v forv recycle to the inlet of the synthesis reactor, use as a fuel gas, or any other desired disposition.

In accordance with one example of actual operation, finely powdered iron is continuouslysubjected to alternate contact with methane and carbon dioxide. In each alternate step, contact is effected at a temperature of about 2000 F. and under a pressure of about 18 atmospheres with the gas lpassing through the flne powder with contact time of about one minute. Y

During introduction of the methane stream, about 95.7 per cent hydrogen in the methane is converted into free gaseous form and withdrawn. This operation is terminated when conversion falls off materially, the powder remaining in the reaction zone at this time being predominantly iron carbide.

Thereafter, a stream of carbon dioxide is introduced under substantially the same reaction conditions as in the previous step. The product gas comprising over 99 per cent of carbon monoxide is likewise separated and withdrawn. When the conversion of carbon dioxide falls appreciably, introduction is terminated and the methane feed is again instituted, the cycle being continuously repeated.

One half of the product gas stream of carbon monoxide is conducted into a separate reactor and passed through a mass of finely powdered, highly oxidized iron particles at a temperature of 2000 F. and under 18 atmospheres pressure. After a contact time of about one minute, the gaseous product withdrawn from contact with the iron oxide is composed essentially of carbon dioxide which constitutes the previously mentioned stream of carbon dioxide passed into contact with the iron carbide powder.

The iron oxide is periodically regenerated by cutting off the supply of carbon monoxide when the conversion of carbon monoxide falls appreciably and injecting it at about 900F. with high pressure steam until substantial reoxidation has occurred. The gaseous product withdrawn from contact with the metal powder after condensation and separation ofthe excess water vapor comprises essentially pure hydrogen.

During continuous cyclic operation in this manner, the particles of the respective powders assume a fine porous condition which appears to greatly facilitate the reactions, and as a result, reaction occurs much more rapidly than would be expected, yielding a high state of purity.

In the foregoing example, the mol ratio of the total hydrogen to carbon monoxide produced closely approximates 3:1. This, however, may be controlledly decreased, as above indicated, by effecting a part at least of the decarbiding with carbon dioxide drawn from any extraneous source.

Referring now to Figure II of the drawing, the

:incoming feed` ofghydrocarbon in pipe I0 mixes with-fa finely :powdered v'metal supplied'tlirough a solids .deliverywduca .conveyor or header-hand elevates it as afsuspension through apipe into carbiding reactor 64 where .reaction- .occurs as before, yielding a suspension of metal carbide in gaseous hydrogen which is withdrawn through ninell` This suspension passes, as indicated, through a heat exchanger 6.5 Which raises it to an even more elevated temperature above about 15Go" F. lfor passage through line .-68 into the bottom of decarbiding reactor 61.

Simultaneously, va portion ofthe metal powder in distributing `header' B12 is picked up by an injected stream of .high .temperature steam intro.- vduced through line 68 and theresulting suspension is carried upwardly .through pipe 6,8 into oxide regeneration reactor vlil where the, .metal particles are converted to an oxide,l meanwhile liberating hydrogen which passes through separator 'H into outlet line l2 leading into synthesis gas header 13.

The oxidized powder discharged by .the separator 1l may, if desired-be advantageously sub.- jected to even more intenseoxidizing conditions to assure maximum conversion` to metal oxide. i

ticles in a stream of product carbon dioxide passes oyerhead. through pipe f1.5 intocarbon dioxide header 1.6, which merges with aforementione pipe .66. leading into. reactor 5l. In addition to the. foregoing reactants supplied toy reactor dfi, through header 15, there is preferably included a. stream of carbon dioxide recovered land recycled from the tail gases of, the hydrocarbon synthesis catalyst reactiom tov be. hereinafter described.

Line 1T receives this carbon dioxide stream and conveys it to exchanger 'l8- where it is raised to. anl elevated temperature and discharged through pipe 'I9z into the carbon. dioxide header T6. It is to be thus. noted that all. of, the various streams introduced into. the reactor-6l are preferably at a high preheat such that, maintenance of the desired temperature, substantially above 100,0D F., as for example above 1,300c F. and pre-fer.- ably above 2000" F., is facilitated, in reactor 8.1 with minimum external heating.

I n reactor 6,1, a, number oi reactions simultaneously ensue. Thus the cobalt carbide powder upon contact With the stream of carbon dioxide, is decarbided, liberating gaseous. carbon monoxide. The carbon monoxide gasr formed reacts immediately with the particles of cobalt oxide. reducing them likewise to the elemental form.

In effect, therefore... the gaseousv reaction, prod.- uct of each reaction involving,` respectis/ely.,Z co,- balt oxide and cobalt carbide, furnishesv a reactant effective to convert. the other solid powder into-` theelementalmetal. The ultimatef result is the natureV of. a. release, or combined oxygen and carbon by the two solid components. toI form product. carbon monoxide, and return bothVK the ses consisting. predominante of. carbon, ciones.-V

ide. -Thefreaction is surprisingly rapdiandyields product carbon monoxide .of increasing purity as the temperature of the reaction` is increased. Separationof this gas from the suspended cobalt particles is effected in separator 8l which discharges the particles down standpipe 82 into distribution header 62, previously mentioned, while the residual gas passes through line. 83 vinto successive, previously mentioned exchangers 'I8 and .6.5, Where it. is cooled to aboutv synthesis temperature.

As in the previous embodiment, .the resulting synthesis gas stream,v after any desired pretreatment or pre-heating not shown, passesv through synthesis reactor 46 and the. product goes. to separationeand recovery'system as in the previous embodiment. The stream of carbon dioxide, separated in gas plant 59, supplies previously mentioned recycle line 11.

It is. to be understood that, in the interest of clarity and simplicity, the foregoing flow sheets omit conventional cooling, circulating and' other equipment obvious to. one skilled in the art, in light. of the present disclosure.

For the same reason, the ovvl sheets omit-fdc.- tails of heating andcooling instrumentalities for maintaining appropriate. reaction temperaturesand heat balance, such as may rbc provided by any skilled engineer familiar with; the ioregcing. Inv general, it may be said that the carbiding and decarbidi-ng reactions are generally endothermic in character, requiring external heat energy which may be furnished in anyl suitable. way,A as for example, by indirect exchange from an external or even an internalsource. On the other hand, the steps of Aoxidizing and deoxidizing the readily oxidizable metal particles, as Well as the catalytic synthesis. of hydrocarbons, are exothermic in character and may require external cooling. Manifesti-32 therefore, the process lends itself to interexchange of thermal energy between the several reactors to the. end that. thermal eiiiciency may reachv a satisfactory level.

The. present. invention. has the advantage of operating at widely varying pressures, from at mospheric upwardly, as high as 600 p. s. i. g. and highen although lowerV pressures the .range of trom. 1GO-300 p.. s. i. g. are preferred..

While the previous embodiments. have been described. largely in termsy `of cobalt andy iron as oxygen and carbon carriers,A a number ofA alternate. metals are obviously available. As above indicated, the metal carbide carrier may com.- prise any metalA readily carbidable at elevated temperaturesv by the carbonaceous. material, and thereafter readily reconvertible to the. elemental metal by contact with carbon dioxide. Included in, this class are, for example, iron, nickeh, cobalt, chromium and man-y others. The oxygen carrier, on the. other hand, may compose any metal readily oxidizable by steam. to an. .oxide which releases .oxygen atr elevated temperatures: inthe presence. ot carbonv monoxide to yieldcarbon dioxide. Examples of such metals are. iron, nickel, cobalt, copper, tin, manganese, antimony, zinc, etc.

In a` combination process as illustrated: in FigureII, wherein the same metal is usedasv a carbide and oxygen carrier,k the class'. is limited accordingly, to metals possessing. mutually; the Af,oliegoing carbiding. and oxidizing proper-.tiesv Itis to, be understood that. the reaction, tem.- peratures,r while. .preferably at an elevated. level, nerertheless wil-L vary in. accordance with. the

9 specific metal selected. In general, as indicated, temperatures above 1000 F. are in all cases necessary for carbiding and decarbiding, whereas somewhat lower temperatures are suitable for oxidation of the metal by steam.

The term ,carbonaceous feed material containing hydrogen contemplates, as above indicated, carbonaceous materials containing substantial proportions of hydrogen and therefore, includes the complete class of hydrocarbons extending from the preferred, normally gaseous hydrocarbons, such as methane, ethane and the like, through the normally liquid boiling hydrocarbons and residual fractions, such as gas oil and even tars, which, however, are, as above indicated, advantageously reacted at high temperatures in the form of a vapor.

In addition, this term contemplates feed materials which, while containing hydrogen and carbon, are not generally spoken of as hydrocarbons. Such, for example, are natural carbonaceous deposits such as coal, which may be fed to the reactor in the finely divided form, but preferably is supplied in liquid forni or vapor form by pressure and temperature in a conventional manner.

Preferably, the carbonaceous feed comprises a sufiicient proportion of hydrogen to yield substantial quantities in the product gas. Therefore, it is advantageous to employ carbonaceous feed materials containing at least, and preferably more than one atom of hydrogen for every two atoms of carbon. This enables the direct production therefrom of a synthesis gas having an Hz/CO ratio of about 1: 1 and upwardly.

Obviously, many modifications and variations of the invention as above set forth may be made without departing from the spirit and scope thereof, and only such limitations should be imposed as are indicated in the appended claims.

I claim:

1. In the conversion of a carbonaceous feed material containing hydrogen into synthesis gas comprising essentially hydrogen and carbon monoxide, the steps which comprise subjecting a metal capable of being readily carbided and subsequently decarbided, and oxidizable by steam to an oxide which is readily reduoible by carbon monoxide, to reaction with said carbonaceous feed material at an elevated temperature at which said metal is thereby carbided, yielding a stream of gaseous hydrogen, subjecting an additional quantity of said metal to contact with water vapor at a high temperature at which the metal is converted to an oxide yielding additional free hydrogen, introducing said metal oxide and metal carbide into a reaction zone in the presence of a substantial stream of carbon dioxide at an elevated temperature at which interaction takes place with the formation of elemental metal and the liberation of a product stream of carbon monoxide and recovering product carbon monoxide thus formed.

2. In the conversion of a carbonaceous feed material containing hydrogen into hydrogen and yso l ii

carbon monoxide, wherein a metal capable of being readily carbided and subsequently decarbided is reacted with said carbonaceous feed material at an elevated temperature to form a carbide of said metal and yield gaseous hydrogen, the improvement which comprises decarbiding said metal carbide by contact with carbon dioxide in the presence' of a readily reducible metal oxide at an elevated temperature in the range at which the reactants interact to yield substantially decarbided and deoxidized metal with the formation of a stream of carbon monoxide.

3. The method according to claim 2 wherein the metal reacted with said carbonaceous feed material comprises metal previously decarbided as aforesaid.

4. In the generation of synthesis gas comprising essentially hydrogen and carbon monoxide from a carbonaceous material containing a substantial proportion of hydrogen, subjecting a metal capable of being readily carbided and subsequently decarbided and capable of oxidizing to to a product which is reducible by carbon monoxide, to a cyclic series of steps comprising converting a portion of said metal to the forni of an oxide, subjecting the second portion of said metal to reaction with said carbonaceous material at an elevated temperature at which the metal is thereby carbided, yielding a stream of gaseous hydrogen, and subjecting the resulting metal oxide and metal carbide, in admixture, to contact with a stream of carbon dioxide, at an elevated temperature at which decarbiding of the metal carbide and deoxidation of the metal oxide occur with the liberation of a product stream of carbon monoxide, and recovering product carbon monoxide thus formed.

5. The method according to claim 4 wherein the said metal remains in finely divided solid particle form.

6. The method according to claim 4 wherein the formation of said metal oxide is effected by treatment with steam.

7. The method according to claim 4 wherein the metal is in the form of finely divided solid particles which are continuously circulated through said series of steps.

CLAUDE W. WATSON.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 1,992,909 Davis Feb. 26, 1935 2,264,427 Asbury Dec. 2, 1941 2,270,897 Roberts, Jr., et al. Jan. 27, 1942 2,436,938 Scharmann et al. Mar. 2, 1948 2,464,532 Sellers Mar. 15, 1949 2,485,875 Gorin et al Oct. 25, 1949 2,523,284 Eastman Sept. 26, 1950 2,535,042 Cohn et al Dec. 26, 1950 FOREIGN PATENTS Number Country Date 51,572 Germany Mar. 17, 1890 

1. IN THE CONVERSION OF A CARBONACEOUS FEED MATERIAL CONTAINING HYDROGEN INTO SYNTHESIS GAS COMPRISING ESSENTIALLY HYDROGEN AND CARBON MONOXIDE, THE STEPS WHICH COMPRISE SUBJECTING A METAL CAPABLE OF BEING READILY CARBIDED AND SUBSEQUENTLY DECARBIDED, AND OXIDIZABLE BY STREAM TO AN OXIDE WHICH IS READILY REDUCIBLE BY CARBON MONOXIDE, TO REACTION WITH SAID CARBONACEOUS FEED MATERIAL AT AN ELEVATED TEMPERATURE AT WHICH SAID METAL IS THEREBY CARBIDED, YIELDING A STREAM OF GASEOUS HYDROGEN, SUBJECTING AN ADDITIONAL QUANTITY OF SAID METAL TO CONTACT WITH WATER VAPOR AT A HIGH TEMPERATURE AT WHICH THE METAL IS CONVERTED TO AN OXIDE YIELDING ADDITIONAL FREE HYDROGEN, INTRODUCING SAID METAL OXIDE AND METAL CARBIDE INTO A REACTION ZONE IN THE PRESENCE OF A SUBSTANTIAL STREAM OF CARBON DIOXIDE AT AN ELEVATED TEMPERATURE AT WHICH INTERACTION TAKES PLACE WITH THE FORMATION OF ELEMENTAL METAL AND THE LIBERATION OF A PRODUCT STREAM OF CARBON MONOXIDE AND RECOVERING PRODUCT CARBON MONOXIDE THUS FORMED. 